org.apache.lucene.analysis.reverse
Class ReverseStringFilter

java.lang.Object
  org.apache.lucene.util.AttributeSource
      org.apache.lucene.analysis.TokenStream
          org.apache.lucene.analysis.TokenFilter
              org.apache.lucene.analysis.reverse.ReverseStringFilter

All Implemented Interfaces:

Closeable

public final class ReverseStringFilter
extends TokenFilter

Reverse token string, for example "country" => "yrtnuoc".

If marker is supplied, then tokens will be also prepended by that character. For example, with a marker of \u0001, "country" => "\u0001yrtnuoc". This is useful when implementing efficient leading wildcards search.

You must specify the required Version compatibility when creating ReverseStringFilter, or when using any of its static methods:

• As of 3.1, supplementary characters are handled correctly

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.lucene.util.AttributeSource

AttributeSource.AttributeFactory, AttributeSource.State

Field Summary

static char	INFORMATION_SEPARATOR_MARKER Example marker character: U+001F (INFORMATION SEPARATOR ONE)
static char	PUA_EC00_MARKER Example marker character: U+EC00 (PRIVATE USE AREA: EC00)
static char	RTL_DIRECTION_MARKER Example marker character: U+200F (RIGHT-TO-LEFT MARK)
static char	START_OF_HEADING_MARKER Example marker character: U+0001 (START OF HEADING)

Fields inherited from class org.apache.lucene.analysis.TokenFilter

input

Constructor Summary

ReverseStringFilter(Version matchVersion, TokenStream in)
Create a new ReverseStringFilter that reverses all tokens in the supplied TokenStream.

ReverseStringFilter(Version matchVersion, TokenStream in, char marker)
Create a new ReverseStringFilter that reverses and marks all tokens in the supplied TokenStream.

Method Summary

boolean	incrementToken()
static void	reverse(Version matchVersion, char[] buffer) Reverses the given input buffer in-place
static void	reverse(Version matchVersion, char[] buffer, int len) Partially reverses the given input buffer in-place from offset 0 up to the given length.
static void	reverse(Version matchVersion, char[] buffer, int start, int len) Partially reverses the given input buffer in-place from the given offset up to the given length.
static String	reverse(Version matchVersion, String input) Reverses the given input string

Methods inherited from class org.apache.lucene.analysis.TokenFilter

close, end, reset

Methods inherited from class org.apache.lucene.util.AttributeSource

addAttribute, addAttributeImpl, captureState, clearAttributes, cloneAttributes, copyTo, equals, getAttribute, getAttributeClassesIterator, getAttributeFactory, getAttributeImplsIterator, hasAttribute, hasAttributes, hashCode, reflectAsString, reflectWith, restoreState, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

START_OF_HEADING_MARKER

public static final char START_OF_HEADING_MARKER

Example marker character: U+0001 (START OF HEADING)

See Also:

Constant Field Values

INFORMATION_SEPARATOR_MARKER

public static final char INFORMATION_SEPARATOR_MARKER

Example marker character: U+001F (INFORMATION SEPARATOR ONE)

See Also:

Constant Field Values

PUA_EC00_MARKER

public static final char PUA_EC00_MARKER

Example marker character: U+EC00 (PRIVATE USE AREA: EC00)

See Also:

Constant Field Values

RTL_DIRECTION_MARKER

public static final char RTL_DIRECTION_MARKER

Example marker character: U+200F (RIGHT-TO-LEFT MARK)

See Also:

Constant Field Values

Constructor Detail

ReverseStringFilter

public ReverseStringFilter(Version matchVersion,
                           TokenStream in)

Create a new ReverseStringFilter that reverses all tokens in the supplied TokenStream.

The reversed tokens will not be marked.

Parameters:

matchVersion - See above

in - TokenStream to filter

ReverseStringFilter

public ReverseStringFilter(Version matchVersion,
                           TokenStream in,
                           char marker)

Create a new ReverseStringFilter that reverses and marks all tokens in the supplied TokenStream.

The reversed tokens will be prepended (marked) by the marker character.

Parameters:

matchVersion - See above

in - TokenStream to filter

marker - A character used to mark reversed tokens

Method Detail

incrementToken

public boolean incrementToken()
                       throws IOException

Specified by:

incrementToken in class TokenStream

Throws:

IOException

reverse

public static String reverse(Version matchVersion,
                             String input)

Reverses the given input string

Parameters:

matchVersion - See above

input - the string to reverse

Returns:

the given input string in reversed order

reverse

public static void reverse(Version matchVersion,
                           char[] buffer)

Reverses the given input buffer in-place

Parameters:

matchVersion - See above

buffer - the input char array to reverse

reverse

public static void reverse(Version matchVersion,
                           char[] buffer,
                           int len)

Partially reverses the given input buffer in-place from offset 0 up to the given length.

Parameters:

matchVersion - See above

buffer - the input char array to reverse

len - the length in the buffer up to where the buffer should be reversed

reverse

public static void reverse(Version matchVersion,
                           char[] buffer,
                           int start,
                           int len)

Partially reverses the given input buffer in-place from the given offset up to the given length.

Parameters:

matchVersion - See above

buffer - the input char array to reverse

start - the offset from where to reverse the buffer

len - the length in the buffer up to where the buffer should be reversed